1. Field of the Invention
The present invention relates to a technical field to which digital image processing pertains. In particular, the present invention relates to an edge detecting apparatus suitable for use in detecting edge components of an image. In addition, the present invention relates to an edge detecting method and program which realize technology for the edge detecting apparatus, and also to, a noise eliminating apparatus, and noise eliminating method and program to which technologies represented by the method and program are applied.
2. Description of the Related Art
Edge detecting technology is used not only in extracting an image edge (outline), but also in improving image quality by enhancing an image edge.
In this technology, noise is simultaneously enhanced depending on an edge enhancing technique. Accordingly, conventionally, various techniques have been attempted.
By way of example, the technique disclosed in Japanese Unexamined Patent Application Publication No. 8-163408 has been proposed by the present assignee. This technique finds an enhanced signal from a secondary differential value of an input image signal. By multiplying the enhanced signal by a noise coefficient, a corrected enhanced signal is obtained. In addition, by performing smoothing in an edge direction (perpendicular to a luminance changing direction), image quality is improved.
In the various techniques, a dedicated circuit for edge detection must be additionally provided. This causes a problem of an increase in circuit size. In addition, in the various techniques, uniform control is only performed for the entirety of a screen such as a frame or field. Thus, processing for each part of the image cannot be performed.